mypy

gh-105936: Properly update closure cells for `setattr` and `__del… #20660

Job	Run time
Run mypy on Tools/cases_generator	16s
Run mypy on Lib/_pyrepl	19s
Run mypy on Tools/check-c-api-docs	20s
Run mypy on Lib/tomllib	15s
Run mypy on Tools/build	16s
Run mypy on Lib/test/libregrtest	19s
Run mypy on Tools/clinic	16s
Run mypy on Tools/peg_generator	17s
Run mypy on Tools/jit	20s
	2m 38s

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